The aim of this study was focused on investigating the effects of chemical modifications and
molecular weight distribution of phytate-removal Soybean Protein Isolate (SPI) hydrolysate on Degree of
Hydrolysis (DH) and the iron binding ability. The chemical modifications included acid treatments,
succinylation, acetylation and phosphorylation. Also the effects of molecular weight distribution of
phosphorylated SPI trypsin hydrolysate on iron binding ability were studied. The results showed that acetic acid
treatment can increase significantly the DH of SPI hydrolysate, but did not increase the iron-binding ability of
SPI hydrolysate. Phosphorylation by Sodium Trimetaphosphate (STMP) can increase significantly the ironbinding
ability, but did not change the DH. The STMP phosphorylation reaction time of 20 min was sufficient
for improving the iron binding capacity and alkaline conditions were beneficial of phosphorylation reaction.
The fraction of molecular size among 3 to 5 kDa exhibited highest iron binding ability, but there were no
significant different in amino acid compositions between the four ultrafilteration fractions.